1. Field of the Invention
The present invention relates to a multi-source surround audio apparatus for performing, in accordance with an instruction from a user, selective surround sound reproduction of audio signals which are inputted from a plurality of sound sources including a DVD.
2. Description of the Background Art
In recent years, in the field of multi-source audio apparatuses which are capable of reproducing audio from a number of audio signal sources including DVDs, there has been a desire for a multi-source surround audio apparatus such that, if an audio signal from a given audio signal source has been recorded so as to have a surround effect, the multi-source surround audio apparatus can properly reproduce a surround audio signal based on each such audio signal. Examples of audio signal sources include: optical recording media (optical disks) such as DVDs, CDs, VCDs, and MDs; magnetic recording media on which MP3 data is recorded (note that MP3 data might also be recorded on an optical disk); FM/AM broadcast; and external optical or electric signal sources.
A multi-source surround audio apparatus must be capable of properly generating a surround audio signal from the audio signal(s) inputted from such a plurality of audio signal sources.
A DVD usually stores at least one of: an audio signal which has been recorded in a 5.1-channel digital surround format (hereinafter a “5.1ch digital surround signal”); and a digitally recorded 2-channel audio signal (hereinafter, a “2ch digital signal”). Note that, in terms of decoding methods, a 2ch digital signal stored on a DVD is similar to that carried by any audio signal source other than DVDs, e.g., a CD, (hereinafter such an audio signal source will be referred to as a “non-DVD audio signal source”).
An analog 2-channel digital surround effector (hereinafter an “analog surround effector”) is conventionally used to generate a 2ch analog surround audio signal based on a 2ch digital signal which is inputted from a DVD or a non-DVD audio signal source. An analog surround effector can also generate a 2ch analog surround audio signal based on a 2ch digital signal inputted from a DVD.
A5.1ch digital surround effector is conventionally used to generate a 5.1ch analog surround audio signal based on a 5.1ch digital surround signal which is inputted from a DVD.
In accordance with a user's request, a multi-source surround audio apparatus needs to switch between available audio signal sources to properly reproduce a surround audio signal from a recorded audio signal. However, in the aforementioned multi-source surround audio apparatus, one needs to switch between a 5.1ch digital surround effector and an analog surround effector, depending not only on the type of the audio signal source but also on the type of audio signal to be reproduced.
For example, the audio signal source may remain to be the same DVD, but the signal reproduced therefrom may be switched from a 5.1ch digital surround signal to a 2ch digital signal. In such a case, it is necessary to accordingly switch from the 5.1ch digital surround effector to the analog surround effector. In another case, one audio signal source may be switched to another, e.g., from a DVD to FM broadcast. Assuming that a 2ch digital signal was being reproduced from the DVD, the same analog surround effector can still be used after switching to FM broadcast.
Thus, with the conventional multi-source surround audio apparatus, a user who wishes to switch the audio signal source to a DVD will need to determine whether the reproduced signal is a 5.1ch digital surround signal or a 2ch digital signal, and accordingly select and instruct either the 5.1ch digital surround effector or the analog surround effector.
Furthermore, a 5.1ch loudspeaker system is required to reproduce a 5.1ch digital surround sound based on a 5.1ch digital surround audio signal which has been properly reproduced from a DVD by means of a 5.1ch digital surround effector. On the other hand, a 5.1ch loudspeaker system is not required to reproduce an audio signal from any non-DVD audio signal source or a 2ch digital signal from a DVD.